Formaldehyde is presently widely employed as a fumigant for disninfecting animal quarters and equipment, and is currently used in livestock and poultry production. The formaldehyde is applied both as a liquid spary and as a gas.
When used as a spray, formalin (commercial liquid formaldehyde, which is approximately a 37% aqueous solution) is diluted about 1 part formalin to 6 parts water and sprayed onto walls, floors and equipment. This liquid spray has an extremely bad odor, and is very toxic. The operator must use a respirator, and even then the fumes may come through, and can be dangerous.
When the formaldehyde is used as a gas, the enclosure to be fumigated is sealed, or if it is equipment that is to be fumigated, it must be placed in a sealed enclosure. Before the enclosure is sealed, it is wetted down well and the temperature is raised to about 95.degree. F. to 100.degree. F., and also a fan is generally used to circulate the air in the enclosure. It is required that the enclosure, and any part thereof to be fumigated, be wetted down because the formaldehyde is not effective as a gas, and the formaldehyde gas employed in the fumigation must go into solution in the water and then come into contact with the surfaces to be fumigated in order to be effective. Although this practice is used regularly in poultry production and on ranches, it is generally inadequate, and there is no assurance of substantially complete disinfecting as with the liquid formaldehyde spray where the operator can be sure that everything to be fumigated is covered. With the use of formaldehyde gas, there is the advantage that the enclosure is sealed up and the operator can leave the area while fumigation is being accomplished, instead of being directly subjected to the fumigation as where the operator is using the spray. However, in addition to the general inadequacy of the formaldehyde gas treatment, it is flammable and explosive, and some places have burned as the result of its use. Also, it is very difficult to seal any relatively large enclosure to prevent the escape of the formaldehyde gas.